Building a USB coders cable

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Jae686
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Building a USB coders cable

Post by Jae686 »

I'm looking forward to build a "coders cable" (USB <-> Dreamcast Serial) .
I've come across mr. henzenmann 's blog post, and while i wait for the quote from siphec regarding their usb-serial adapters...
  • I'm looking to two alternative usb - serial adapters
  • the uUSB-MB5 converter
    pros :
    .Very small (probably it may fit inside the dreamcast)
    .TX, RX already at 3.3v levels
    Cons:
    .No RI signal (according to chaos schematics, its not required for the dc.)
    .No external clock signal (although the USB converter supports up to 1 Mbps with hw handshake)
    .Its not FTDI based, but there are linux drivers at the manufacturer's website
  • the Mini USB adapter used for the arduino mini
    pros :
    .Includes RI signal
    .FTDI based
    Cons
    .TX, RX at 5 v (therefore requiring additional IC to handle the 5 <-> 3.3 conversion)
    . it uses a B type USB connector (therefore i will need to carve a bigger hole on the dreamcast for the USB plug)
    . no pins for a external clock signal (allthough i may solder it on the pin of the ftdi ic it self, since its a SMD)
Any considerations i've may have left out ?
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henzenmann
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Re: Building a USB coders cable

Post by henzenmann »

Jae686 wrote:
  • I'm looking to two alternative usb - serial adapters
  • the uUSB-MB5 converter
    pros :
    .Very small (probably it may fit inside the dreamcast)
    .TX, RX already at 3.3v levels
    Cons:
    .No RI signal (according to chaos schematics, its not required for the dc.)
    .No external clock signal (although the USB converter supports up to 1 Mbps with hw handshake)
    .Its not FTDI based, but there are linux drivers at the manufacturer's website
That adapter is indeed nice and small. If you don't need the 24MHz clock, then you would only have to add the reset transistor and be good to go.
You could leave a little space to add the oscillator later on...

Also the CP2102 chip used in this adapter should be supported by Linux out of the box, just like the FTDI one.
Jae686 wrote:[*] the Mini USB adapter used for the arduino mini
pros :
.Includes RI signal
.FTDI based
Cons
.TX, RX at 5 v (therefore requiring additional IC to handle the 5 <-> 3.3 conversion)
. it uses a B type USB connector (therefore i will need to carve a bigger hole on the dreamcast for the USB plug)
. no pins for a external clock signal (allthough i may solder it on the pin of the ftdi ic it self, since its a SMD) [/list]
While the connector is bigger, it also sticks out while on the other adapter it is aligned to the board. So you'd have to make the opening big enough to
fit the cable...

If I were to build another one of these, I think I'd go with the smaller adapter and try to fit it all inside the DC :-)
Jae686
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Re: Building a USB coders cable

Post by Jae686 »

Yup, thats probably what i'm going to do.

Thanks for the advice!
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Re: Building a USB coders cable

Post by Jae686 »

In your circuit what IC you used for the Interface Switiching (buffer tri-state?)
And how did you wired it ?
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henzenmann
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Re: Building a USB coders cable

Post by henzenmann »

Jae686 wrote:In your circuit what IC you used for the Interface Switiching (buffer tri-state?)
And how did you wired it ?
74VHC244, just like in Chaos's original schematic: http://f17.aaa.livedoor.jp/~takotako/dc ... t232bm.php (3rd schematic, titled "Dreamcast Serial Port Adaptor (for FT232BM base unit)").
The VHC version of this chip allows to interface between 5v and 3.3v logic. It should also work with 3.3v on both sides, but other chips might work as well in that case and be easier to find.
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Re: Building a USB coders cable

Post by Jae686 »

Well, i've finished my coders cable.

The Pcb containing the 74HC244 is a bit....big (I'm probably going to etch a pcb to make it smaller.....) but the setup works as intended.


Pics:

Image

Image

Now I think I've got the goods to start coding.

Btw, I've built dc-tools according to the tutorial at dcs.

But on the makefile, the cdrecord option regarding the cd drive must be on a diferent format.
CDRECORD = cdrecord dev='/dev/scd0' speed=8
my makefile:

Code: Select all



CDRECORD	= cdrecord dev='/dev/scd0' speed=8
#CDRECORD	= cdrecord dev=ATAPI:0,0,0 speed=8
SCRAMBLE	= /home/jaerder/development/dreamcast/tools/scrambler/scrambler
DD		= dd
CP		= cp
MKISOFS		= mkisofs
CAT		= cat
TOUCH		= touch
1ST_READ	= ../target-src/1st_read/1st_read.bin

all: $(1ST_READ) audio.raw burn-audio data.raw burn-data

audio.raw:
	$(DD) if=/dev/zero of=audio.raw bs=2352 count=300

burn-audio: audio.raw
	$(CDRECORD) -multi -audio audio.raw
	touch burn-audio

1st_read.bin: $(1ST_READ)
	$(SCRAMBLE) $(1ST_READ) 1st_read.bin

data.raw: tmp.iso IP.BIN
	( cat IP.BIN ; dd if=tmp.iso bs=2048 skip=16 ) > data.raw

tmp.iso: 1st_read.bin burn-audio
	$(MKISOFS) -C `$(CDRECORD) -msinfo` -o tmp.iso 1st_read.bin

burn-data: data.raw
	$(CDRECORD) -xa data.raw
	rm -f audio.raw data.raw burn-audio

.PHONY : clean
clean:
	rm -f tmp.iso burn-audio 1st_read.bin

.PHONY : distclean
distclean: clean
	rm -f audio.raw data.raw
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BB Hood
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Re: Building a USB coders cable

Post by BB Hood »

Good job :)
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